diff --git a/evmcc/BasicBlock.cpp b/evmcc/BasicBlock.cpp
index 5271c984fa..3a2c1c5487 100644
--- a/evmcc/BasicBlock.cpp
+++ b/evmcc/BasicBlock.cpp
@@ -33,19 +33,29 @@ void BasicBlock::Stack::push(llvm::Value* _value)
 
 llvm::Value* BasicBlock::Stack::pop()
 {
-	if (m_backend.empty())
-	{
-		// Create PHI node
-		if (m_llvmBB->empty())
-			return llvm::PHINode::Create(Type::i256, 0, {}, m_llvmBB);
-		return llvm::PHINode::Create(Type::i256, 0, {}, m_llvmBB->getFirstNonPHI());
-	}
-
-	auto top = m_backend.back();
+	auto top = get(0);
 	m_backend.pop_back();
 	return top;
 }
 
+llvm::Value* BasicBlock::Stack::get(size_t _index)
+{	
+	if (_index >= m_backend.size())
+	{
+		// Create PHI node for missing values
+		auto nMissingVals = _index - m_backend.size() + 1;
+		m_backend.insert(m_backend.begin(), nMissingVals, nullptr);
+		for (decltype(nMissingVals) i = 0; i < nMissingVals; ++i)
+		{
+			m_backend[i] = m_llvmBB->empty() ?
+				llvm::PHINode::Create(Type::i256, 0, {}, m_llvmBB) :
+				llvm::PHINode::Create(Type::i256, 0, {}, m_llvmBB->getFirstNonPHI());
+		}
+	}
+
+	return *(m_backend.rbegin() + _index);
+}
+
 void BasicBlock::Stack::dup(size_t _index)
 {
 	m_backend.push_back(get(_index));
@@ -54,7 +64,8 @@ void BasicBlock::Stack::dup(size_t _index)
 void BasicBlock::Stack::swap(size_t _index)
 {
 	assert(_index != 0);
-	std::swap(get(0), get(_index));
+	get(_index); // Create PHI nodes
+	std::swap(*m_backend.rbegin(), *(m_backend.rbegin() + _index));
 }
 
 }
diff --git a/evmcc/BasicBlock.h b/evmcc/BasicBlock.h
index 3c47db328f..598ab731ca 100644
--- a/evmcc/BasicBlock.h
+++ b/evmcc/BasicBlock.h
@@ -21,7 +21,7 @@ public:
 		llvm::Value* pop();
 
 		/// Gets _index'th value from top (counting from 0)
-		llvm::Value*& get(size_t _index) { return *(m_backend.rbegin() + _index); }
+		llvm::Value* get(size_t _index);
 
 		/// Duplicates _index'th value on stack.
 		void dup(size_t _index);
diff --git a/evmcc/Compiler.cpp b/evmcc/Compiler.cpp
index 0d3487e101..1e2982b296 100644
--- a/evmcc/Compiler.cpp
+++ b/evmcc/Compiler.cpp
@@ -213,8 +213,7 @@ std::unique_ptr<llvm::Module> Compiler::compile(const dev::bytes& bytecode)
 		{
 			auto inst = static_cast<Instruction>(bytecode[currentPC]);
 
-			// Disable for now
-			//gasMeter.check(inst);
+			gasMeter.check(inst);
 
 			switch (inst)
 			{
diff --git a/evmcc/GasMeter.cpp b/evmcc/GasMeter.cpp
index 2006f319f0..a40b8cb5cc 100644
--- a/evmcc/GasMeter.cpp
+++ b/evmcc/GasMeter.cpp
@@ -49,6 +49,33 @@ uint64_t getStepCost(dev::eth::Instruction inst) // TODO: Add this function to F
 	}
 }
 
+bool isCommitTrigger(Instruction _inst)
+{
+	switch (_inst)
+	{
+	case Instruction::STOP:
+	case Instruction::CALLDATACOPY:
+	case Instruction::CODECOPY:
+	case Instruction::MLOAD:
+	case Instruction::MSTORE:
+	case Instruction::MSTORE8:
+	case Instruction::SSTORE:
+	case Instruction::JUMP:
+	case Instruction::JUMPI:
+	case Instruction::JUMPDEST:
+	case Instruction::GAS:
+	case Instruction::CREATE:
+	case Instruction::CALL:
+	case Instruction::CALLCODE:
+	case Instruction::RETURN:
+	case Instruction::SUICIDE:
+		return true;
+
+	default:
+		return false;
+	}
+}
+
 }
 
 GasMeter::GasMeter(llvm::IRBuilder<>& _builder, llvm::Module* _module):
@@ -72,8 +99,20 @@ GasMeter::GasMeter(llvm::IRBuilder<>& _builder, llvm::Module* _module):
 
 void GasMeter::check(Instruction _inst)
 {
+	if (!m_checkCall)
+	{
+		m_checkCall = m_builder.CreateCall(m_gasCheckFunc, m_builder.getIntN(256, 0));
+	}
+	
 	auto stepCost = getStepCost(_inst);
-	m_builder.CreateCall(m_gasCheckFunc, m_builder.getIntN(256, stepCost));
+	m_blockCost += stepCost;
+
+	auto isTrigger = isCommitTrigger(_inst);
+	if (isTrigger)
+	{
+		m_checkCall->setArgOperand(0, m_builder.getIntN(256, m_blockCost));
+		m_checkCall = nullptr;
+	}	
 }
 
 }
\ No newline at end of file
diff --git a/evmcc/GasMeter.h b/evmcc/GasMeter.h
index e2ee26a716..057391102c 100644
--- a/evmcc/GasMeter.h
+++ b/evmcc/GasMeter.h
@@ -19,7 +19,11 @@ public:
 	void check(dev::eth::Instruction _inst);
 
 private:
+	/// Cumulative gas cost of a block of instructions
+	/// @TODO Handle overflow
+	uint64_t m_blockCost = 0;
 	llvm::IRBuilder<>& m_builder;
+	llvm::CallInst* m_checkCall;
 	llvm::GlobalVariable* m_gas;
 	llvm::Function* m_gasCheckFunc;
 };